The present invention relates to an improvement in a dynamic viscoelasticity device for detecting interdependence between the viscoelastic property of a material and temperature, time, and frequency and the like, in order to improve stability in a temperature rise from a low temperature of -150.degree. C. in a heating furnace for changing the temperature of a material.
Conventional heating furnaces used for raising temperature from a low temperature of -150.degree. C. and for keeping the temperature constant, have a configuration as shown in FIG. 2. Specifically, an outer cylinder 3 in which a heater wire 2 is disposed, is fixed in an adiabatic portion 7 made of an adiabatic material and, further, there is a sample 12 which is attached to the inside thereof with an insertable probe 11. Cool air introduced by a hose 9 of a liquid nitrogen vaporization type cooling device which is not shown, is passed via a cool air introduction hole 4 through meshes 13 provided at a thrust portion of the outer cylinder 3 around which the heater wire 2 is wound, to be directly sprayed upon the sample.
The conventional device which directly applies cool air to a sample, has a problem that the linearity of a temperature rise from low temperature is adversely affected by temperature fluctuation at a thermocouple portion disposed in the vicinity of the sample which is caused by an air current produced inside the cylinder.